China has another new development under construction in the disputed South China Sea just as Xi Jinping completes a friendly tour of the region

Beijing appears to have very quickly and quietly built a new structure in the contested South China Sea.

The news comes as China's President Xi Jinping makes the first state visit to Manila by a Chinese leader in 13 years.

After visits to Papua New Guinea and Brunei in the last week, Xi told his counterpart that friendship was "the only right choice" for China and the Philippines.

Newly self-confessed sinofile, Philippine President Rodrigo Duterte, is walking a delicate line between Washington and Beijing as great power tension in the Pacific is on the rise.

While Philippine President Rodrigo Duterte and his Chinese counterpart, Xi Jinping, met in Manila on Tuesday, analysts at a Washington-based think tank were poring over satellite images of unidentified new structures in the contested South China Sea.

Timing is often everything and according to the Asia Maritime Transparency Initiative, Beijing appears to have built a new structure on one of the features in the South China Sea in no time at all.

With the contest for supremacy in the Pacific between Beijing and Washington reaching a fever pitch this week, Xi told his counterpart that friendship and "win-win" cooperation was the only way forward for China and the Philippines, regardless of Manila's history as a staunch US ally.

"Given the profound and complex changes in the world, good-neighborliness and friendship is the only right choice for China and the Philippines, two developing countries and emerging economies in Asia, and our peoples have higher expectations for stronger ties and cooperation," Xi said upon his arrival on Tuesday.

Those comments ring hollow with the identification of an unannounced and unidentified new structure near the contested Paracel Islands.

Beijing appears to have built a new structure on one of the features in the South China Sea, according to a new report from the Asia Maritime Transparency Initiative.

That's no moon

AMTI CSIS / Digital Global

Recent satellite imagery of Bombay Reef in the Paracel Islands shows that China has installed a new platform at the largely untouched South China Sea feature, a territory that is also claimed by Taiwan and Vietnam.

Located at the southeastern edge, the structure is ideally located directly adjacent to the region's busy shipping lanes that channel traffic between the Paracel and the Spratly Islands, where Beijing has also installed military facilities.

The structure was not noted in images taken around April and first appeared at the reef on satellite imagery dated July 7.

"The modest new structure appears to be anchored on the north edge of the reef and is topped by a radome and solar panels," AMTI reported on Tuesday.

Given the Bombay Reef's important strategic location and the fact that the regional rivals, have both made strident claims to the reef and other areas around the Paracels, analysts have suggested the platform could become the first of many such designs.

"(There is) the possibility that the structure's rapid deployment could be repeated in other parts of the South China Sea.

"The structure is topped by a radome measuring roughly 20 feet (6 meters) in diameter and an array of solar panels covering more than 1,300 square-feet (124 meters). The superstructure hides any other facilities or equipment that the platform may contain," the AMTI observed.

The Paracel Islands, like the rest of the chain, has been administered by China since 1974. But until a few months ago, the only artificial structure on the mostly-submerged reef was a run-down lighthouse

According to AMTI, the closest Chinese outposts are Lincoln Island, some 39 nautical miles to the northeast, Woody Island, about 47 nautical miles to the north, Duncan Island, roughly 50 nautical miles to the northwest, and Triton Island about 75 nautical miles to the west.

This is not a lighthouse

AMTI has identified features, including the Bombay Reef's strategic location that, aside from being used to serve as a navigational aid, the structure's radome may have unconfirmed military uses.

"The radome is relatively small, especially compared to large sensor arrays built on nearby Woody Island or on China's major bases in the Spratly Islands, so its capabilities are also likely modest," the think tank noted.

The news comes as Xi and Duterte continue to build on an entirely new, somewhat unexpected alliance.

Xi landed in Manila Tuesday in a visit that makes up for a chill 13 years since the last state visit of a Chinese president, Jiang Zemin during the Gloria Arroyo administration.

In that time the Philippines had taken a very a strong line on China's behavior in the disputed seas, even taking China to an international tribunal.

But since the combustible Duterte has imposed his brash style of authoritarian populism on an impressionable Philippines government, relations with Beijing have gone into a kind of overdrive.

Within hours of touching down, the leaders touted some 39 new deals. Most critically, a preliminarily agreement to cooperate on oil and gas exploration, a move that is likely to rile the many Filipinos wary of Chinese territorial expansionism and untrusting of Beijing's intentions.

A 2016 ruling by the Permanent Court of Arbitration in a case filed by Manila clarified, among other issues, that the Philippines had sovereign rights to the energy reserves at around Reed Bank. It also put to bed China's nine-dash line claim to swathes of the region, which the senate said was "unlawful and expansive."

The ruling brought many Filipinos out onto the streets in support.

When China subsequently rejected the Hague tribunal's ruling outright, that support quickly turned to fury.

Activists raise clinched fists as they march towards the Chinese consulate for a protest in Manila on February 10, 2018, against Beijing's claims in the South China Sea after installing military facilities and equipment on them. TED ALJIBE/AFP/Getty Images

But Duterte has repeatedly downplayed, mocked and even threatened to end the cornerstone Philippine-US alliance in order to reassure Beijing of his "love" and commitment to bilateral rapprochement.

Robust US pushback welcome

Prior to their talks, Duterte held a welcome ceremony in Xi's honor at the presidential palace featuring a 21-gun salute and traditional dances.

However, his ostentatious displays of Sinocism could run dangerously against the tide of popular opinion that he has so far used adroitly to navigate through a largely welcome crackdown on drugs and regional terrorism.

"On the surface, Philippine president Rodrigo Duterte is overseeing a new 'golden age' in bilateral relations with China," Heydarian said.

Beyond the warming diplomatic exchanges with Beijing, however, Manila is tacitly reviving security cooperation with Washington, its sole treaty ally, through expanded joint military exercises and overall deepening defense cooperation"

According to Heydarian, Duterte's quiet pivot back to the US is driven by the ongoing doubts in Manila over China's intrusion into contested waters, as well as the absence of closure on major Chinese investments.

He added that there is now "growing confidence in the resolve of the United States and its key allies to draw a firm line in the South China Sea."

Certainly, the administration of US President Donald Trump has presented a far more prickly proposition for Beijing on both economic and geopolitical fronts.

Trump has slapped tariffs on a further US$200 billion of Chinese imports, while rousing support for further freedom of navigation operations in the contested waters.

"The Philippines have quietly welcomed a more robust pushback against China," Heydarian said.